Pumps are well known to move fluids from at least a first location to a second location. A large number of pump configurations are known, each with particular advantages and disadvantages and which may have been designed for particular uses in a variety of fluid-moving industries.
It is well known to provide pumping apparatus situated in subterranean wellbores for pumping fluid therefrom to the surface. Conventionally, a prime mover, such as an electric motor, has been located at the pump or mechanically connected thereto so as to permit actuation of pumps, such as a rod pump or progressive cavity pump, to lift liquids such as produced fluids and accumulated fluids therefrom. In the case of wellbores, particularly those situated in remote locations, it is desirable to situate the pump within the wellbore and to actuate the pump remotely. Typically, many of the pumps known in the art require two conduits, one to provide a motive force to operate the pump, such as in the case of hydraulic-actuated pumps, and the second to permit production of the fluids to surface.
In the case of said wellbores, it is known to provide remotely actuated pumps, such as those which are actuated by sonic or acoustic pressure waves (U.S. Pat. No. 4,295,799 to Bentley, U.S. Pat. No. 1,730,336 to Bellocq, U.S. Pat. Nos. 2,444,912, 2,553,541, 2,553,542, 2,553,543, and 2,953,095, to Bodine Jr.)
Further it is known to provide remotely actuated pumps which are actuated by alternately applying and releasing pressure at discharge of the pump. One such pump is taught in U.S. Pat. No. 4,390,326 to Callicoate which teaches an annular external piston and an internal piston movable in concentric annular and internal chambers. The internal chamber has an inlet end and an outlet end fit with one-way valves. The internal piston divides an internal barrel into a lower chamber and an upper chamber. The lower chamber has an inlet valve and an outlet valve through which pumped fluid is transferred to the upper chamber. The upper chamber has an outlet valve through which fluids are transferred into conduit thereabove. As the pump is stroked, fluid from below the pump is sucked into the lower chamber on the upstroke. On the downstroke, the fluid in the lower chamber is transferred to the upper chamber through the valve positioned therebetween. On the next upstroke, while fluid is being drawn into the lower chamber, the fluid in the upper chamber is transferred from the space above, through the upper chamber's outlet valve, while the external piston causes the fluid in the space above to be pumped to surface. Pressure is applied cyclically to the conduit causing the pistons to be moved downhole. An energy storing means, such as a spring, returns the pistons uphole as the pressure is relieved at the conduit discharge.
Remotely actuated pumps are particularly advantageous for use in oil wells to produce hydrocarbons to surface and for deliquification of gas wells, wherein the pump can be situated at or near the perforations, and can be actuated to pump accumulated liquids such as water and condensate, to the surface which, if left to accumulate in the conduit through which the gas is produced causes backpressure on the formation which impedes gas flow and which may eventually kill gas production.
In the case of deliquification of gas wells, conventionally beam pumps or hydraulic pumps, including piston downhole pumps and jet pumps have been used, as have electric submersible pumps and progressive cavity pumps however the cost of these pumps is relatively high. Regardless the use, providing power for actuation of such pumps in remote locations, size of the pumps and interference due to produced gas during use in deliquification have typically been problematic.
Further, other technologies such as foam lift, gas lift and plunger lift have been used to deliquify gas wells. In some of the known technologies, the gas well must be shut-in for at least a period of time to permit sufficient energy to be built up to lift the accumulated fluids which results in, at best, a cyclic production of gas from the wellbore.
Clearly, there is interest in a large variety of fluid-moving industries for technologies, including pumping apparatus, which have relatively low power requirements, are capable of being remotely actuated and which have a relatively high pumping efficiency. Of particular interest are pump apparatus for use in producing fluids from wellbores, including but not limited to deliquifying of gas wells to improve and maintain production therefrom.